The purpose of the rammer is to drive the shell, upon charging of the piece, into its rammed position in the barrel, with at least one of the bourrelets of the shell in such close contact with the lands of the barrel rifling that the shell remains in the rammed position even at the maximum elevation of the piece. This is necessary in order to permit introduction of the propellant powder charge into its position in the charge space situated behind the rammed shell. The normal charging procedure begins by being the shell into the immediate vicinity of the open rear section of the artillery piece, for example on an in-swinging charge cradle, after which a rammer of one type or another drives the shell into its rammed position. Since, as has already been mentioned, there must be space behind the shell for the propellant powder charge itself, the distance by which the rammer must move the shell into the barrel is relatively long.
Moreover, the shell must be driven in with a certain force in order for it to remain there even when the piece is at its maximum elevation. In the case of purely axially displaceable rammers, this results in comparatively long constructions. On the other hand the known more compact rammer constructions have had to rely on a relatively long so-called free flight for the shell, which means that it makes contact with the rammer only during a relatively short part of the ramming distance from the charge position to the rammed position, but that the shell during this relatively short part of the ramming distance is given a sufficient speed so that, after the contact with the rammer has ceased, it can continue, by means of a combination of the acquired speed and the intrinsic gravity, into its rammed position with sufficient force to give the desired engagement in the barrel grooving.
An example of such a rammer with a long free flight for the shell is described in German Offenlegungsschrift 3,607,006. However, a long free flight constitutes a factor of unreliability, since in this case there is poor control of how good the ramming actually is in each particular case.
The purpose of the present invention is primarily to provide a rammer with a short free flight and a very compact construction. In addition, the construction of the rammer according to the invention includes a small number of simple and strong components.
Furthermore, the construction according to the invention has made it possible, in the case of hydraulic operation of the rammer, to limit the number of hydraulic connections to a minimum, and at the same time, due to the special design of the rammer, these connections can be made in the form of fixed connections on the breech casing of the piece, which therefore do not participate in the recoil of the piece, which is also very advantageous as regards both operational reliability and servicing requirements.
These advantageous characteristics of the rammer according to the present invention come fully into play in connection with modernizing older types of armored-turret-protected pieces which were originally charge manually, of which there are a very large number dating from the sixties and the beginning of the seventies and whose value would be increased to a very great extent if they could be provided with wholly automatic or semi-automatic charging systems instead of their previous manually charging systems. Since these pieces are already mounted in armored turrets with limited internal space, the requirement for compact charging systems is very significant. In addition, it must be possible to mount the charging system with place without significant interference in the artillery piece system as such or its possible auxiliary systems.
The rammer according to the present invention is thus primarily intended for those artillery pieces which are separately charged with the shell and propellant powder charges (powder bags). Upon charging of the piece, the rammer will move the shells from a charging position wholly or partly outside the rear charge opening of the piece to the rammed position of the shell ahead of the charge space intended for the propellant powder in the rear section of the barrel. As has already been mentioned, this displacement is at present relatively long and will probably be longer in future, since in recent times shells continue to become longer and narrower in line with the increase in the firing ranges of artillery pieces. Regarding the requirement for driving the shells at a certain force into the rammed position so that they remain there even when the piece is at its maximum elevation, it should be mentioned that the armored-turret-protected pieces are often of the howitzer type and have a maximum elevation of 75.degree.-80.degree. relative to the ground level.
The shells are brought to the charging position immediately outside the rear charge opening of the barrel either on an in-swinging charge cradle, usually provided with special securing members for the shells, or else the shells are placed manually in the charging position. With an appropriate design of the suspension of the charge cradle, the latter can be made to swing the shell at least partly into the charge opening of the piece. This of course facilitates the ramming.
The rammer according to the present invention, like most other rammers, is designed to grip behind the shell and push it forwards from the charge cradle to the rammed position of the shell inside the barrel. As has already been pointed out, the shortest possible free flight for the shell is desired here. The inventors have now succeeded in achieving a maximum ram travel for the rammer according to the invention within a minimum space requirement by dividing the rammer into two piston cylinder systems which are connected to each other by means of a transverse arm and are axially displaceable parallel to each other and to the barrel from and to their respective zero positions. These piston cylinder systems define a primary and secondary rammer whose combined ram travel corresponds to the distance which the rammer is to move the shell, and the cylinder of the primary rammer is arranged non-displaceable relative to the breech casing of the piece, while the transverse arm is connected to the displaceable piston rod of the primary rammer, and the cylinder of the secondary rammer is securely connected to the other end of the transverse arm. Moreover, the projection direction of the primary rammer piston is directed rearwards along the barrel of the piece and identical to the retraction direction of the secondary rammer piston. This means that the projection direction of the secondary rammer piston is directed forwards in the barrel direction. The two cooperating rammers are moreover mounted on the piece in such a way that, when the primary rammer is completely projected and the secondary rammer completely retracted, the front part of the secondary rammer, that is to say the front part of its piston rod, is immediately behind a shell situated on the charge cradle or the like. With this design of the rammer, the ramming is effected by means of a combination of projection of the secondary rammer and retraction of the primary rammer.
According to this invention, the rammer is additionally designed in such a way that, as long as it does not extend into the charge space of the barrel, it can be swivelled aside about the attachment of the transverse arm on the primary rammer, so that the secondary rammer is completely turned away parallel to the side of the barrel axis, that is to say away from the rear charge opening of the barrel.
By means of retraction of the primary rammer piston, the whole rammer can thus be transferred to a rest position alongside the barrel.
The possibility of moving the secondary rammer to the side is also used with advantage after ramming in order to facilitate the swinging-in of the charge cradle with a new shell. This possibility also means that, upon firing, no separate space for the rammer is required behind the piece upon recoil of the latter.